If you work in the electrical, electronic, or automotive industries, you’ve likely heard of manufacturing methods that balance precision and efficiency. One such method gaining traction is the low-pressure infusion process—a technique that injects plastic into molds under gentle pressure to create delicate, high-quality components. But what exactly is this process, how does it work, and why should you consider it for your production needs?
In this guide, we’ll break down the low-pressure infusion process from start to finish, explore its key features, highlight real-world applications, and address common questions. Our goal is to help engineers, production managers, and product designers make informed decisions about whether this process fits their projects.
1. First: Defining the Low-Pressure Infusion Process
At its core, the low-pressure infusion process (also called low-pressure injection molding) is a manufacturing technique that injects molten plastic into a mold and cures it rapidly—all within a relatively low pressure range. Unlike traditional high-pressure injection molding (which uses 10–200MPa), low-pressure infusion operates at just 0.15–4MPa—a pressure gentle enough to protect delicate molds and components while still ensuring precise plastic flow.
The process follows three simple stages:
- Material preparation: Heat plastic to a molten state (temperature depends on the material, usually 150–250°C) to ensure it flows easily.
- Low-pressure injection: Use a specialized machine to inject the molten plastic into a custom mold at 0.15–4MPa. The low pressure prevents mold damage and reduces stress on the plastic.
- Rapid curing: Let the plastic cool and harden quickly inside the mold (cure time ranges from 10–60 seconds, depending on part size). Once cured, remove the finished component from the mold.
Key Differentiator: The low pressure and fast curing make this process ideal for small, sensitive parts that would crack or deform under high-pressure methods.
2. 7 Key Features of the Low-Pressure Infusion Process
The low-pressure infusion process stands out for its unique characteristics—each designed to solve common challenges in manufacturing delicate components. Let’s explore these features in detail, with data and examples to illustrate their value:
Feature 1: Low-Pressure Operation (0.15–4MPa)
As the name suggests, low pressure is the process’s defining trait. This gentle pressure offers two big benefits:
- Mold protection: Low pressure reduces wear and tear on molds, extending their lifespan by 30–50% compared to high-pressure molding. For example, a mold used for electrical connectors might last 100,000 cycles with low-pressure infusion, vs. 60,000 cycles with high-pressure methods.
- Component safety: Delicate parts (like thin circuit boards or tiny sensors) won’t crack or warp under low pressure. A manufacturer of automotive microchips reported zero component damage after switching to low-pressure infusion—down from 8% damage with high-pressure molding.
Feature 2: Rapid Curing to Shorten Production Cycles
Fast curing is another major advantage. Most low-pressure infusion parts cure in 10–60 seconds, which cuts production time dramatically.
- Why it’s fast: The low-pressure process uses plastics with fast-curing formulas (e.g., thermoset resins or modified thermoplastics) that harden quickly when cooled.
- Efficiency boost: A factory making USB connectors switched to low-pressure infusion and reduced their production cycle from 2 minutes per part (high-pressure) to 30 seconds per part. This let them increase daily output from 10,000 to 20,000 connectors—doubling efficiency without adding extra machines.
Feature 3: Ideal for Tiny, Sensitive Components
Low-pressure infusion excels at manufacturing small, intricate parts that require precision. Common examples include:
- Electrical connectors: Tiny pins and slots (as small as 0.5mm) need perfect alignment—low pressure ensures plastic fills every detail without damaging the mold.
- Circuit boards: Delicate traces on PCBs (printed circuit boards) can’t withstand high pressure—low-pressure infusion coats them evenly for insulation without cracking.
- Automotive sensors: Small sensors (used in engine control units) need airtight packaging—low pressure ensures plastic seals every gap without warping the sensor.
Case Study: A smartphone manufacturer used low-pressure infusion to make charging port connectors (size: 5mm x 2mm). The process delivered 99.8% defect-free parts, with all connectors fitting perfectly into phone bodies—up from 95% defect-free parts with traditional molding.
Feature 4: Precision-Designed Equipment
Low-pressure infusion machines are built for accuracy. Unlike generic injection molding machines, they include features to control pressure and flow precisely:
- Pressure regulators: Maintain a steady 0.15–4MPa pressure to avoid fluctuations that cause defects.
- Temperature control: Keep plastic at a consistent molten state (±2°C) to ensure smooth flow.
- Micro-injection nozzles: Tiny nozzles (0.2–1mm diameter) deliver plastic to small mold cavities without waste.
Pro Tip: When choosing a machine, look for models with digital pressure displays—they let you monitor and adjust pressure in real time, reducing errors.
Feature 5: Specialized Mold Design for Low-Pressure Flow
Molds for low-pressure infusion need custom designs to accommodate the gentle plastic flow. Unlike high-pressure molds (which rely on force to push plastic), low-pressure molds use:
- Wider gates: Larger openings (1–3mm) let plastic flow easily into the mold without pressure buildup.
- Smooth internal surfaces: Polished mold walls reduce friction, helping plastic fill every detail.
- Vent holes: Small holes (0.1–0.2mm) release trapped air—preventing bubbles in the finished part.
Example: A mold for a 3mm x 1mm sensor housing includes 4 vent holes and a 2mm gate. This design ensures plastic flows evenly, with no bubbles or empty spots in the housing.
Feature 6: Plastic Materials with Good Flow and Fast Curing
The success of low-pressure infusion depends on choosing the right plastic. Most processes use materials with two key properties:
- High flowability: Plastics that melt into a thin, runny liquid (e.g., polyethylene, polypropylene, or modified ABS) can fill small mold cavities easily.
- Fast curing: Materials that harden quickly (e.g., thermoset epoxy resins or fast-cure nylon) reduce production time.
Below is a table of common materials used in low-pressure infusion, with their uses and properties:
| Material | Key Properties | Best For | Example Parts |
| Polyethylene (PE) | High flow, low cost, chemical-resistant | Insulation, simple connectors | Wire insulation, basic sensor housings |
| Polypropylene (PP) | Stiff, heat-resistant (up to 160°C) | Automotive components, electrical parts | Car sensor housings, circuit board frames |
| Modified ABS | Impact-resistant, good surface finish | Delicate electronics | USB connectors, smartphone charging ports |
| Thermoset Epoxy Resin | Fast curing (10–30 seconds), high strength | High-precision parts | Microchip packaging, tiny gears |
Feature 7: Environmental Friendliness
Low-pressure infusion is more eco-friendly than many manufacturing methods, thanks to two factors:
- Less material waste: The precise injection and fast curing mean less excess plastic (usually just 5–10% waste, vs. 15–20% with high-pressure molding).
- Lower energy use: Low-pressure machines require less electricity to operate—using 20–30% less energy than high-pressure models. A factory in Germany reported a 25% drop in monthly energy bills after switching to low-pressure infusion for connector production.
3. Top Applications: Where Low-Pressure Infusion Shines
The low-pressure infusion process is most widely used in two industries—electrical/electronic and automotive—where small, precise components are in high demand. Here’s how it’s applied in each:
Application 1: Electrical and Electronic Industry
This industry relies on low-pressure infusion for parts that need insulation, precision, and durability:
- Circuit board (PCB) packaging: Coats PCBs with plastic to protect them from moisture and dust.
- Connector manufacturing: Makes tiny USB, HDMI, and power connectors with perfect pin alignment.
- Sensor encapsulation: Seals small sensors (e.g., temperature or humidity sensors) to make them waterproof.
Example: A tech company used low-pressure infusion to encapsulate 5mm x 3mm humidity sensors for smart home devices. The process created a waterproof seal that let the sensors work in bathrooms and kitchens—with zero failures in 10,000 test units.
Application 2: Automotive Industry
Automotive manufacturers use low-pressure infusion for delicate components in engines, dashboards, and safety systems:
- Engine sensors: Makes small sensors (e.g., oil pressure sensors) that withstand high temperatures without warping.
- Dashboard electronics: Produces tiny switches and LED connectors that fit into tight spaces.
- Safety system parts: Creates precision components for airbags and anti-lock braking systems (ABS) that need zero defects.
Case Study: A car manufacturer switched to low-pressure infusion for engine temperature sensors (size: 8mm x 4mm). The process reduced defect rates from 5% to 0.5% and cut production time by 40%—saving the company $200,000 annually.
4. Yigu Technology’s Perspective on the Low-Pressure Infusion Process
At Yigu Technology, we’ve supported over 200 clients in the electrical/electronic and automotive industries with low-pressure infusion solutions. From our experience, this process is a game-changer for manufacturing small, sensitive parts—it balances precision, speed, and cost in a way high-pressure methods can’t. We recommend it for clients making components smaller than 10mm x 10mm, as it eliminates damage and reduces waste. We also help design custom molds and select the right materials, ensuring each project meets production goals. For companies looking to boost efficiency and quality in delicate part manufacturing, low-pressure infusion isn’t just an option—it’s the most reliable choice.
5. (FAQ)
Q1: Can low-pressure infusion be used for large parts (e.g., 50mm x 50mm)?
No—low-pressure infusion works best for small parts (usually under 10mm x 10mm). For larger parts, the low pressure may not push plastic to fill the entire mold evenly, leading to empty spots or defects. High-pressure injection molding is better for large components.
Q2: How much does a low-pressure infusion machine cost?
Prices range from \(20,000–\)100,000, depending on size and features. Small machines (for parts under 5mm x 5mm) cost \(20,000–\)40,000, while larger machines (for parts up to 10mm x 10mm) cost \(50,000–\)100,000. The investment pays off quickly—most clients recoup costs in 6–12 months via reduced waste and faster production.
Q3: Is low-pressure infusion more expensive than traditional high-pressure molding?
Initially, yes—low-pressure machines and molds cost slightly more. But over time, it’s cheaper: lower mold replacement costs (molds last longer), less material waste, and lower energy bills mean long-term savings. For example, a company making 10,000 connectors monthly saved $5,000 per month after switching to low-pressure infusion.
